Technical Abstract:
Seeds survive for years under dry conditions but then viability crashes without warning. Efforts to provide high quality seeds to customers, breed longer-living seeds, or to investigate the underlying causes of deterioration during storage prompt the need for a reliable measure of the longevity phenotype without years of waiting or an ‘after the fact’ assessment. ‘Accelerated aging’ or ‘controlled deterioration’ tests promised to predict which seed lots would age relatively fast or slowly by measuring their performance under high humidity and high temperature conditions. We evaluated how well longevity of seeds exposed to ‘accelerated aging’ challenges corresponds to survival under dry, high temperature conditions and to dry, low temperature conditions typically used in seed banks. We used seeds from the Brassicaceae family because of their wide global distribution, documented range of longevities and a priori genomic information. One to several populations of 7 species including 4 ecotypes of A. thaliana, were selected for use. Germination time courses were compared among seed lots stored at high (75%) and low (14%) relative humidity and elevated temperature (35 and 45C) with seeds from the same species stored dry at 5C for 30-40 years. There was no correlation between seed lot response to high and low RH at elevated temperatures. Moreover, there was no correlation between longevity of samples subjected to ‘accelerated aging’ conditions and average longevity reported for species by the seed bank. However, there was a significant correlation between longevity of species exemplars stored at low humidity and elevated temperatures and average longevity reported for species by the seed bank. We conclude that ‘accelerated aging’ tests using high humidity have limited utility for predicting seed longevity among seed lots within a species or closely related species.